Clamp for can body forming machine



Oct. 29, 1968 v w, F, WOLFE 3,407,765

CLAMP FOR CAN BODY FORMING MACHINE Filed Nov. 5, 1966 4 Sheets-Sheet 1INVENTOR- MMYNE E 14 00 5 ram 52, z/vaaae' MAQTENS v ATTO'ENEKSL Oct.29, 1968 Q w. F. WOLFE Q N 3,407,765

CLAMP FOR CAN BODY FORMING MACHINE Filed Nov. 5, 1966 f Sheets-Sheet 2INVENTOR. WAYNE A WOLFE BY Fan .4 5 44/0555 6 444a TEA/.5

Oct. 29, 1968 w. F. WOLFE 3,407,765

CLAMP FOR CAN BODY FORMING MACHINE Filed Nov. 3, 1966 V 4 Sheets-Sheet 5'INVENTOR. Hwy/V6" F. WOAF' POM/L52, 44/0555 a Amer-6N5 Oct. 29, 1968 w.F. WOLFE CLAMP FOR CAN BODY FORMING MACHINE 4 Sheets-Sheet 4 Fil q Nov.5, 1966 INVENTOR.

m, WM 0 wk msm 5m} .,NE V4 gm 1 W5 United States Patent 3,407,765 CLAMPFOR CAN BODY FORMING MACHINE Wayne F. Wolfe, Orange, Calif., assignor toUnited Can Company, Fullerton, Califl, a corporation of Delaware FiledNov. 3, 1966, Ser. No. 591,762 7 Claims. (Cl. 113-8) This inventionrelates to machines for forming can bodies from flat blanks, and, moreparticularly, to apparatus for alternately clamping and releasing a canblank against a mandrel on which the can body is formed.

Generally in machines for forming metal can bodies, a series of flatmetal blanks are fed past a station at which the two side edges of eachblank are folded to form elongate hooks. Then at a subsequent station,the blanks are formed around a cylindrical mandrel by a pair of formingwings which open and close about the mandrel much like a pair of pliersto inter-engage the hooked edges so that the blanks retain theircylindrical shape. The mandrel then is expanded to tightly engage thehooks and the seam is pounded from below by a bumper mechanism to firmlyclench the edges. The mandrel usually is cantilevered so that thecylindrical can body can then be conveyed off the free end of themandrel to receive can ends at another station.

In order to prevent misalignment of the blank and to provide an anvil toreinforce the mandrel against the bumping force, it is essential thatthe blank be clamped against the mandrel from above while the wings formthe cylindrical body and the blank is expanded and bumped. This can bedone by an elongate clamping shoe which is disposed over the mandrel andreciprocates from a clamping position to a release position. However, inmachines producing four hundred can bodies per minute and more, theclamp must engage and release the blank at a tremendous rate. Moreover,it must exert sufficient force to securely hold a can blank in placewhile it is being shaped into a body, yet because the cantileveredmandrel is subject to bending, it is critical that the clamp not applyexcessive pressure. Thus, uniformity of clamping pressure is essential.The prior art devices have encountered considerable problems inaccomplishing these objects in the extremely fast operation required foran economical can forming machine.

One prior art approach employs sliding wedges to actuate the clampingshoe. One wedge remains fixed during normal operation. The other isforced between the fixed wedge and the shoe to apply pressure to theshoe, and then is forced out from the wedging position to release thepressure after the blank has been formed. However, application ofsufficient force to operate the movable wedge can cause difficulty inhigh speed operation. Releasing the pressure can be a particular problemas the wedges sometimes freeze together. Moreover, the desired goal ofuniformity of pressure is difficult to achieve.

A refinement of that prior art apparatus instead actuates the clampingshoe by forcing a wiper cam against an inclined surface formed on thetop of the upper wedge. However, dirt and other foreign matter canaccumulate on both the inclined surface and the wiper cam causingvariances in the amount of pressure applied by the shoe.

Moreover, the impact of the wiper cam on the inclined surface impartsconsiderable shock to the machine when operating at high speeds, andtends to wear and gall both parts. Irregularities developed from theimpact can vary the clamping pressure and even cause the wiping cam tolock against the inclined surface in the clamped position.

This invention is directed to an improved can forming machine structurewhich eliminates the use of sliding wedges or impacting cam surfaces toactuate the clamp, and substitutes well lubricated rotary bearingsurfaces which are less subject to wear, and are less likely to be3,407,765 Patented Oct. 29, 1968 affected by surface irregularities. Theadvantage of the rotary bearing surfaces are compounded at high speedssuch as those at which modern can forming machines operate.

The rotary bearing surfaces are provided in a can forming machineconstructed in accordance with this invention by opposed concave arcuatebearing surfaces in a portion of the clamping shoe assembly and anelongate shaft which is rotatably mounted alongside it. Two spaced-aparttongue portions of a link are inserted in the concavities to connect theclamping shoe assembly and shaft. Each of the tongue portions has anarcuate bearing surface conforming to the mating concave bearingsurface. As the shaft is oscillated, the link forces the clamping shoeto the clamping position and then removes the pressure so that the canbody can be conveyed on.

A further feature of this invention resides in the use of an overloaddevice in the connecting rod. which oscillates the elongate shaft. Iftwo can bodies rather than one are inadvertely placed on the mandrel, orif for any other reason excessive pressure would otherwise be applied tothe mandrel, the overload device prevents the application of theexcessive pressure so that the cantilevered mandrel is not bent from itsnormal position.

These and other features, objects and advantages of this invention willbe apparent from the following detailed discussion when read withreference to the accompanying drawings, in which:

FIG. 1 is an end elevation view of a can body forming machineconstructed in accordance with this invention with portions cut away toshow the mandrel, the forming wings, alilid portions of the mechanismfor actuating the clamping s oe;

FIG. 2 is a vertical longitudinal section through the mandrel andclamping device taken generally along lines 2--2 of FIG. 1;

FIG. 3 is a vertical cross-section taken generally along the lines 33 ofFIG. 2 illustrating the structure of the clamping device and the formingwings, and showing the clamping shoe in the clamping position;

FIG. 4 is a partial cross-section similar to FIG. 3 illustrating theclamp actuating mechanism in the release position;

FIG. 5 is an enlarged perspective view of one of the plate springs forholding the two adjusting wedges in tight abutment; and,

FIG. 6 is a somewhat schematic perspective illustration of the mechanismfor driving and coordinating actuation of the clamping device and thecan forming wings.

Referring to FIGS. 1-3, the can body machine includes a main frame 2from which a cylindrical can body mandrel or horn 4 is cantilevered. Apair of rails 6 and 8, one of which has a chamfered inner edge 10, aredisposed on opposite sides of the mandrel 4 to support a fiat can bodyblank 12 by its edges in position over the mandrel. The can body blankis moved through the can forming station by a feed bar (not shown) toabutment with a positioning lug 14 along each rail 6 and 8. A pair offorming wings 16 supported from the frame are adapted to be pivoted froman open position (shown in phantom in FIG. 1) above the blank 12 toforce it off of the inner edges of the rails 6 and 8 and fold the blankabout the cylindrical mandrel to form a cylindrically shaped can body.The inner surface 18 of each forming wing 16 is semi-cylindrical toconform to the shape of the mandrel. Each of the forming wings 16 ispivotally mounted on a pin 20 at the lower end of a support bracket 22which depends from the main frame 2.

Referring to FIGS. 1 and 6, the drive for the wings includes a pair ofvertical actuating rods 24 mounted on cranks 26 fixed to parallel drivenshafts 28 which rotate to cause the actuating rods 24 to reciprocate upand down.

A roller at the upper end of each actauting rod 24 is mounted in anadjusting slot 32 of a lever 34 which is pivotally mounted on a stubshaft 36 supported on the frame 2. Through the action of the actuatingrods, the lever 34 oscillates up and down as the driven shaft 28rotates. A short connecting rod 37 aifixed between the distal end ofeach lever 34 and a respective one of the forming wings 16, opens andcloses the forming wings responsive to rotation of the driven shafts 28and oscillation of the lever 34. Each of the actuating rods 24 includesa spring barrelled shock absorber 38 for buffering unusual loads andshocks applied to the wings.

The above-described structure, as well as the expending and seam bumpingmechanism, is generally similar to that disclosed in applicants priorPatent No. 3,100,470, issued Aug. 13, 1963, and reference is made tothat patent for additional details of the can forming machine notspecifically described herein.

Referring now to FIGS. 2 and 3, the support bracket 22 partially housesa clamping shoe member which includes a clamping shoe 40 and rods 44.The clamping shoe 40 extends out of the lower portion of the bracket andrests on the mandrel 4. The sides of the support bracket 22 fix theclamping shoe 40 against lateral movement. Pins 42 extend from theclamping shoe into the vertical guide rods 44 which are received invertical sleeves through the support bracket to fix the shoe againstlongitudinal movement relative to the support bracket. The guide rods 44and the clamping shoe 40 are free to reciprocate vertically within thesupport bracket, but the clamping shoe is urged down against the mandrel4 by light springs 46 housed Within the bracket and the ends of theclamping shoe. The trailing edge 48 of the clamping shoe is chamfered sothat a can blank conveyed in the direction of the arrow 50 strikes thechamfered shoe edge 48 and raises the shoe sufficiently that the blankcan pass into position between the shoe and the cantilevered mandrel.

An adjusting wedge assembly includes a lower wedge 52 which extendslongitudinally through the support bracket 2, and is fixed againstlongitudinal movement relative to the bracket by plungers 54 each ofwhich has a body portion 56 received in an aperture in the support armand a reduced diameter tip 58 which fits into an aperture 60 in thelower wedge 52. Springs 62 through the plungers 54 urge the wedgeassembly upward. The lower wedge 52 has two longitudinally spacedinclined surfaces 64 on its upper face, both inclined from one end 66 ofthe wedge toward the other 68. An upper adjusting wedge 70 has twoinclined surfaces 72 on its lower face which rest on the upper inclinedsurfaces 64 of the lower wedge. The inclined surfaces of the upper andlower wedges are held in tight engagement by a pair of plate springs 74(see also FIG 5) of generally W-shaped configuration which are attachedto the respective wedge members by dowel pins 76 extending from thewedges through apertures 78 in the plate springs to form a connectedwedge assembly.

The longitudinal position of the upper wedge 70 relative to the lowerone 52 is fixed by a pair of bolts 80 which extend through threadedbores in opposite end portions of the lower wedge and abut the ends 82and 84 of the upper Wedge. By adjusting the penetration of the bolts 80,the longitudinal position of the upper wedge relative to the lower canbe adjusted. A lock nut 86 on each bolt holds against movement from theadjusted position under operation.

A bearing block 88 fixed to the frame 2 rotatably mounts an elongateshaft 90 directly over the upper wedge 70. A cap 102 bolted on one endof the shaft 90 bears against one end of the block 88 and a collar 103fixed on the other end of the shaft 90 bears against the other end ofthe block 88 to hold the shaft longitudinally relative to the frame 2.The shaft 90 has a longitudinal groove 92 formed in its lower sideforming an elongate rotary bearing surface of arcuate concavecross-sectional configuration, and the upper wedge 70 has a similargroove 94 formed in its upper surface. An elongate toggle link 96 has atongue portion 98 and 99 along each of its two edges, the tongues beingspaced-apart by a short body portion 100. The upper tongue 98 extendsthrough a slot in the bottom of the bearing block and into the hearinggroove 92. The lower tongue 99 extends into the bearing groove 94. Thetoggle link is held longitudinally by the portions 104 and 107 of theblock 88 at each end of the slot 105.

Referring now particularly to FIGS. 1 and 6, the main drive Shaft 106 ofthe machine is rotated by a suitable motor (not shown) to rotate adriving gear 108 in the direction of the arrows. The driving gear 108rotates a pair of gears 110 fixed on parallel shafts 28 which rotate thecranks 26 and reciprocate the actuating rods 24. Each of the rods 24oscillates one of the levers 34 about its stub shaft 36 to pivot theforming wings 16 about pins 20 and open and close the wings 16 about themandrel 4, thereby forming the cylindrical can body. A rotary cam 112having a raised cam portion 114 on its periphery is also mounted on oneof the driven shafts 28. A crank arm 116 fixed on one end of a torsionrod 118 which is rotatably mounted on the machine frame has a roller 120on its free end which rides on or off the raised portion 114 of the camto oscillate the torsion rod 118. A second crank arm 122 fixed to theother end of the torsion rod 118 is connected to the lower end of aconnecting rod 124 thereby causing the connecting rod 124 to reciprocateas the torsion rod 118 oscillates. The upper end of the connecting rod124 is connected to one arm 126 of a pivot crank 128 which is pivotallymounted on a crank pin 130 fixed to the frame of the machine. A secondarm 132 which extends from the pivot crank in the opposite direction isconnected to one end of a connecting link 134 which has its other endpivotally connected to a crank arm 136 on the collar 103 which is keyedon the end of the elongate clamp driving shaft 90.

As is illustrated most clearly in FIGS. 3 and 4, as the elongate clampdriving shaft 90 oscillates through an angle a, preferably about 10, thetoggle link 96 moves from a position in which a plane P through thecenters of its arcuate bearing surfaces is aligned with the longitudinalaxis 138 of the clamp driving shaft 90 (as shown in FIG. 3) to aposition in which the plane P is not aligned with the shaft axis 138 (asshown in FIG. 4). In the aligned position of FIG. 3, the link 96 forcesthe upper 70 and lower 52 wedges downward against the guide rods 44,thereby applying pressure to the clamping shoe 40 and forcing it downtightly against a can blank 12 to clamp the blank to the mandrel 4. Asthe clamp driving shaft 90 is oscillated to the position of FIG. 4, thedistance from the shaft axis 138 to the lower bearing surface of thetoggle link is shortened so that pressure is relieved from the wedges 70and 52 and the formed can body is released from the clamping shoe 40 andmay be conveyed away from the forming station. In the released position,the springs 62 urge the wedge assembly upward away from the rods 44 tomaintain good contact between the bearing surfaces of the toggle link 96and the bearing grooves 92 and 94, and also to take the weight of thewedge assembly off of the shoe. After a new can body blank comes underthe clamping shoe, the clamp driving shaft 90 returns to the alignedposition to force the wedge assembly against the upper end of the rods44 and repeat the sequence, the operation of the forming wings 16, theexpanding and seam bumping mechanisms (not shown), and the clamping shoebeing carefully coordinated through the common drive.

While this invention has been described with reference to a particularembodiment, the scope of the invention should not be limited to thatembodiment, but instead should be measured by the following claims.

I claim:

1. In a can forming machine having an elongate mandrel about which a canbody is formed and a shoe for alternately clamping and releasing a canblank against the mandrel, means for actuating the clamping shoecomprising:

a clamping shoe assembly;

means mounting the clamping shoe assembly for reciprocation toward andaway from a can forming mandrel to clamp and release a can blank on themandrel;

an elongate shaft rotatably mounted alongside the clamping shoeassembly;

opposed concave arcuate bearing surfaces on the shaft and clamping shoeassembly;

a toggle link connecting the clamping shoe assembly and shaft toreciprocate the clamping shoe assembly responsive to oscillation of theshaft, said toggle link including two spaced-apart bearing surfaces ofconvex arcuate cross-sectional configuration each received in andconforming to a respective one of the concave bearing surfaces; and,

means for oscillating the elongate shaft to actuate the clamping shoe.

2. In a can forming machine having an elongate mandrel about which a canbody is formed and a shoe for alternately clamping and releasing a canblank against the mandrel, means for actuating the clamping shoe inaccordance with claim 1 wherein the means for oscillating the elongateshaft includes:

a power-driven main drive shaft;

a reciprocable rod eccentrically connected to the elongate shaft andoperably connected to the drive shaft for oscillating the elongate shaftresponsive to rotation of the main drive shaft; and,

overload means in said rod for absorbing excessive shock applied to saidshoe.

3. In a can forming machine having an elongate mandrel about which a canbody is formed and a shoe for alternately clamping and releasing a canblank against the mandrel, means for actuating the clamping shoe inaccordance with claim 1 wherein:

the concave bearing surfaces are the walls of elongate parallel groovesin the clamping shoe assembly and elongate shaft; and,

the toggle link is an elongate member extending along the grooves andhaving the convex bearing surfaces formed on two of its longitudinaledges.

4. In a can forming machine having an elongate mandrel about which a canbody is formed and a shoe for alternately clamping and releasing a canblank against the mandrel, means for actuating the clamping shoe inaccordance with claim 1, and further comprising spring means maintainingthe bearing surfaces of the toggle link in contact with the bearingsurfaces of the shaft and clamping shoe assembly.

5. In a can forming machine having an elongate mandrel about which a canbody is formed and a shoe for alternately clamping and releasing a canblank against the mandrel, means for actuating the clamping shoe inaccordance with claim 1, wherein the clamping shoe as sembly includes:

a clamping shoe member for engaging a blank on the mandrel, saidclamping shoe member being mounted for reciprocation over the mandrel;

an adjusting wedge assem'bly mounted over the clamping shoe member forvertical reciprocation relative thereto between a clamping position inwhich the wedge assembly applies downward pressure to the clamping shoemember, and a release position in which the wedge assembly is spacedfrom the clamping shoe member, the concave bearing surface of theclamping shoe assembly being on the adjusting wedge assembly; and,

spring means for urging the adjusting wedge assembly upward away fromthe clamping shoe member and maintaining contact between the respectivebearing surfaces of the toggle link, shaft and clamping shoe assembly.

6. In a can forming machine:

5 a frame;

a generally cylindrical can forming mandrel cantilevered from the frame;

a support member depending from the frame over the mandrel;

a pair of opposed forming wings pivotally mounted on the support memberand adapted to be pivoted between an open position above a can blank andthe mandrel and a closed position around the can blank and mandrel;

an elongate clamping shoe supported on the mandrel and having a clampingsurface on its lower face;

means on the mounting member fixing the clamping shoe againstlongitudinal or side-ways movement;

spring means connected to said shoe and to said mounting member urgingsaid clamping surface against the mandrel;

a chamfered edge on the clamping shoe for cooperation with a can bodyblank to raise the clamping surface from the mandrel;

wedge assembly mounted for reciprocation in the support member above theclamping shoe, said wedge assembly including a lower wedge having itsupper surface inclined and an upper wedge having its lower surfaceinclined;

plate spring means connected to said upper and lower wedges to hold saidinclined surfaces in abutment;

an elongate groove of arcuate cross-sectional configuration formed inthe upper surface of the upper wedge;

means for moving one of .said wedge members relative to the other toadjust the distance between the clamping surface and said groove;

an elongate shaft oscillatably mounted on the can forming machine overthe wedge assembly;

an elongate groove of arcuate cross-sectional configuration formed inthe elongate shaft;

an elongate toggle link including a pair of elongate tongues inserted insaid grooves, said tongues being spaced-apart by a body member and eachincluding an elongate bearing surface of convex cross-sectionalconfiguration conforming to the groove in which it is inserted;

spring means urging the wedge assembly upward against the toggle link;and,

means for oscillating the elongate shaft to alternately force theclamping shoe against a can body on the mandrel and release the downwardpressure from the shoe.

7. In a can forming machine in accordance with claim 55 6, wherein themeans for oscillating the elongate shaft includes:

a power-driven main drive shaft; a reciprocable rod eccentricallyconnected to the elongate shaft and operably connected to the driveshaft for oscillating the elongate shaft responsive to rotation of themain drive shaft; and, overload means in said rod for absorbingexcessive shock applied to said shoe.

References Cited UNITED STATES PATENTS 2,181,319 11/1939 Flugge 113-73,192,755 7/1965 LaXo 113-7 3,320,916 5/1967 Werge 113-4 CHARLES W.LANHAM, Primary Examiner.

RONALD D. GREFE, Assistant Examiner.

1. IN A CAN FORMING MACHINE HAVING AN ELONGATE MANDREL ABOUT WHICH A CANBODY IS FORMED AND A SHOE FOR ALTERNATELY CLAMPING AND RELEASING A CANBLANK AGAINST THE MANDREL, MEANS FOR ACTUATING THE CLAMPING SHOECOMPRISING: A CLAMPING SHOE ASSEMBLY; MEANS MOUNTING THE CLAMPING SHOEASSEMBLY FOR RECIPROCATION TOWARD AND AWAY FROM A CAN FORMING MANDREL TOCLAMP AND RELEASE A CAN BLANK ON THE MANDREL; AN ELONGATE SHAFTROTATABLY MOUNTED ALONGSIDE THE CLAMPING SHOE ASSEMBLY;